Blood-Brain Barrier Integrity and Immune Dynamics in Neuropsychiatric Sequelae of Post-SARS-CoV-2 onset ME/CFS versus Pre-Pandemic ME/CFS Patients

PROJECT SUMMARY/ABSTRACT Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), is a long-term disabling condition with a wide range of symptoms, often triggered by acute infection. The CDC estimates that in 2022, over 3.5 million Americans are living with ME/CFS, and this number continues to increase as many Long COVID patients develop ME/CFS. Profound neurocognitive sequelae are highly prevalent in ME/CFS. The underlying pathophysiologic mechanism that drives neurocognitive impairments in post-infectious chronic conditions remains poorly understood, hindering the development of therapeutic interventions. Studies in chronic viral infections recognize that the trafficking of proinflammatory monocytes in the brain drives disruption of the blood-brain barrier and promotes a neuroinflammatory state. We hypothesize that post-SARS-CoV-2 onset ME/CFS patients and pre- pandemic ME/CFS patients have similar blood-brain barrier (BBB) disruption that is mechanistically linked to circulating proinflammatory analytes (cytokines and chemokines), altered BBB endothelial integrity, and a subtype of proinflammatory peripheral blood mononuclear cells (PBMCs) known as intermediate monocytes. Thus, disruption in BBB integrity promotes persistent neuroinflammation and altered neuronal activity, contributing to neuropsychiatric sequelae in both pre- and post-pandemic ME/CFS patients.Additionally, there is evidence supporting glymphatic system dysfunction in ME/CFS, which further contributes to the perpetuation of the neuroinflammatory state. We propose cross-sectional imaging to assess BBB integrity, with neuropsychiatric assessments and immunophenotyping in 100 post-SARS-CoV-2 onset ME/CFS patients and 100 who have pre- pandemic ME/CFS patients. In addition, we will incorporate 100 participants as a control group of SARS-CoV-2 infected individuals who fully recovered without lingering symptoms from our team NIH-funded similar study in a Long COVID cohort. First, we aim to assess BBB integrity in post-pandemic ME/CFS (vs. pre-pandemic ME/CFS) and its contribution to neuropsychiatric conditions. BBB integrity will be evaluated with a non-contrast magnetic resonance imaging technique that uses water-extraction-with-phase-contrast-arterial-spin-tagging (WEPCAST), to determine BBB permeability to small molecules. We have shown this to be sensitive to BBB change in mild cognitive impairment and are currently using this technique in other neuro-infectious diseases. Second, we aim to assess cross-sectional links between circulating soluble markers, PBMC-associated markers, and BBB permeability to small molecules in post SARS CoV-2 onset ME/CFS patients and pre pandemic ME/CFS. We hypothesize that both groups will exhibit similar levels of soluble markers promoting PBMC trafficking to brain and promoting monocyte activation, disruption of soluble markers that promote endothelial integrity & higher levels of cell-surface proteins that promote PBMC diapedesis into brain will be associated with higher PS values and greater alterations in the cognitive and psychiatric domains. Findings will inform next steps in the development of therapeutic approaches to minimize neuroinflammation in Long COVID.